2 chargers vs one?

[Garry]

On one of the RC car forums I'm on, theres currently a thread on charging 2 packs of six NiCD or NiMH cells at once. The obvious answers are either one charger capable of charging both the packs separatley, or two stand-alone chargers. However, one member thinks its fine to use one charger that'll handle more than 12 cells, just wire up the two packs in series.

I've tried to explain that this is dangerous as the packs have been discharged at different rates, and would probably lead to overcharging/venting, and possible explosion.

Can someone point me to an article, guide or post to support the 2 chargers vs one theory?